Process for preparing n-butyraldimine



Patented May 13, 1947 UNITED STATE PROCESS FOR PREPARING n-BUTYRALDIMINE Marshall B.

ore to Eastman N. Y., a corporation H Brimer, James E.

Harold Von Bramer, Kingsport,

Kodak Company, Rochester,

f New Jersey Magoffin, and Tenn assign- No Drawing. Application June 9, 1945,

Serial N 4 Claims.

This invention relates to a process for ing n-butyraldimine.

It is known that acetaldehyd'e reacts with ammonia to produce acetaldehyde-ammonia. This addition compound can be formed by slowly introducing acetaldehyde into liquefied anhydrous ammonia, or by introducing dry ammonia into an ethereal solution of acetaldehyde or by gradual addition of a concentrated aqueous solution of ammonia to acetaldehyde at low temperatures. If acetaldehyde-ammonia is desiccated over sulfuric acid, it loses water, becoming transformed into polymeric ethylideneimine (or acetaldimine).

We have now found that n-butyraldimine can be produced in good yields directly from n-butyraldehyde and ammonia, if the n-butyraldehyde is reacted with the ammonia in the presence of sufficient water.

It is, accordingly, an object of our invention to provide an improved process for preparing n-butyraldimine. Other objects will become apparent hereinafter.

In accordance with our invention, we prepare n-butyraldimine by reacting one molecular proportion or n-butyraldehyde with at least one molecular proportion of ammonia, in the presence of from about 2 to about 4 molecular proportions of water for each molecular proportion of ammonia. Ordinarily there is little advantage in employing more than 2 molecular proportions of ammonia for each mole of n-butyraldehyde. The reaction proceeds rapidly at ordinary temperatures and is exothermic. It is advantageous to cool the reaction mixture to hold the ,temperature of the reaction mixture at from about to about C. It is advantageous to add the n-butyraldehyde gradually to a water solution of ammonia. The water solution is preferably vigorously agitated during the addition of the n-butyraldehyde. When the reaction is complete (within a few minutes from the time the last of the n-butyraldehyde is added gradually to a vigorously agitated water solution of ammonia), the reaction mixture separates into two layers upon stopping the agitation. The upper layer consists of n-butyraldimine and n-butyraldehyde (usually '75 to 80 per cent by weight of the layer is n-butyraldimine), and the lower layer is large- 1y water. The two layers are easily separable and the lower aqueous layer can be drawn off from the reaction vessel.

The upper layer consisting essentially of nbutyraldimine and a minor proportion of n-butyraldehyde, is useful for a number of purposes without further treatment; for example, it can prepar be treated with hydrogen, in the presence of a metal hydrogenation catalyst, to produce n-butylamineif ammonia in excess of the n-butyraldehyde is'added. See our copending application Serial No. 598,644, filed of even date herewith. To remove the n butyraldehydefrom the upper layer, the layer can be subjected to distillation under reduced pressure until the nbutyraldehyde is removed.

Our process can be operated as a continuous or as a batch process. When operating in a continuous manner, the n-butyraldehyde and water solution of ammonia (e. g. 28 per cent by weight) are introduced simultaneously into one end of a cylindrical reaction vessel. The reaction mixture is passed through a zone of vigorous agitathe reaction is rapidly completed) into a zone of comparative qu1escence, where separation of the layers takes place. By means of appropriately spaced exit ports, the n-butyraldimine layer and the water layer can be continuously withdrawn from the system. The continuous process has the advantage over the batch process of producing n-butyraldimine of uniform quality in easily regulated quantities.

The following example will serve to illustrate further the manner of practicing our invention.

Example 2190 g. (29.2 mol.) of 96 per cent n-butyraldehyde were added gradually to 1776 g. of vigorously agitated 28 per cent (by weight) aqueous ammonia (29.2 mol. of ammonia and 10.9 mol. of water) over a period of two hours. The reaction mixture was cooled to hold the temperature at about 25 C. during the addition of the nbutyraldehyde and the vigorous agitation was continued for about of the n-butyraldehyde. The agitation was then stopped and the reaction mixture allowed to settle. The lower aqueous layer was drawn oil, leaving the upper layer (2139.1 g.) which contained n-butyraldimine and n-butyraldehyde, the n-butyraldimine constituting from '75 to per cent by weight of the layer. The mixture of n-butyraldimine and n-butyraldehyde can be employed as such or subjected to distillation un der reduced pressure to remove the n-butyrab dehyde.

In the foregoing example, the ratio oi moles of ammonia to mole of water is about 122.4. In a similar manner n-butyraldimine can be prepared using ratios of moles of ammonia to moles of water of 1:2, 1:3 or 1:4 for example.

What we claim as our invention and desire to hour after the addition be secured by Letters Patent of the United water solution containing at least one molecular States is.

n-butyra dehyde with at least one molecular profor each molecular proportion of ammonia, while portion of ammonia, in the presence of from maintaining the reaction mixture at a temperaabout 2 to about 4 molecular proportions or watei ture of from about 15 to about 30 for each mole of ammonia 2. A process for preparing n-butyraldimine MAR-SHALL R. BRIMER. comprising reacting one molecular proportion of JAMES E. MAGOFFIN. n-butyraldehyde with at least one molecular pro- HAROLD VON BRAMER. portion of ammonia, in the presence of from about 2 to about 4 molecular proportions of REFERENCES CITED Water for each mole of ammonia at a tempera" The following references are of record in the ture of from about to about 320 C. d 15 file of this patent:

3. A process for preparing nutyral imine comprising adding n-butyraldehyde to a vigor- UNITED STATES PATENTS ously agitated water solution of ammonia, the Numb N t Water solution containing at least one molecular 2,045,574 dk June 30 193 proportion of ammonia for each molecular pro- 2,097 3o Lutz 2 1937 portion of n-butyraldehyde and containing from 2,219, 79 Vanderbilt t 29 9 about 2 to about 4 molecular proportions of water 2,319,843 Clark et al. May 25, 1943 for each molecular proportion of ammonia.

4. A process for preparing n-butyraldimine FOREIGN PATENTS comprising adding n-butyraldehyde to a vigor- Number Country Date ously agitated water solution of ammonia, the 290,808 Germany Mar. 15, 1916 

